REGULATED EXOCYTOSIS IN DEVELOPING & NEOPLASTIC PANCREATIC ACINAR CELLS

我们项目的总体目标是确定 发育中胰腺分泌调节的生物起源。我们 先前的研究表明，出生前1至2天，腺泡细胞 对促分泌素刺激的反应是细胞内 第二个按摩水平，但不耦合此事件的胞吐，尽管 观察到细胞外途径的所有细胞器都 礼物受调节的胞吐作用对激素刺激的反应， 出生后约24-48小时起作用（分泌发生）。我们 研究表明，分泌发生与rab 3D（a 一个专门用于酶原分泌发生的标记物与一个 rab 4（出生后24-48小时）显著但短暂的出现在 与肌动蛋白末端共定位的细胞顶端细胞质 网，而不是与分泌或内吞途径的膜。我们 假设rab 4的瞬时表达与 肌动蛋白“钳”的成熟可能是一个终末事件， 导致调节胞吐作用成熟的事件。我们打算 进一步研究这一系统，以确定相关因素 用于分泌生成。具体目标是（1）描述 rab 3和rab 4在分泌发生中的生理意义 关于磷酸化状态、与调节蛋白的相互作用 (e.g., rab GDI和可能参与肌动蛋白结合的蛋白质），以及 评价细胞系AR 42 J的功能，AR 42 J的分泌途径受调节 可以是经尿道诱导的，并且其中rab蛋白的特异性mRNA被 用反义核苷酸消除;（2）检测 其他小GTP结合蛋白和SNARE家族成员， 在分泌发生过程中受到发育调节;（3）研究 在确定的条件下在器官培养中进行分泌发生， 确定候选激素对受调节的 分泌;和（4）检查腺泡细胞肿瘤和衍生的诱导型肿瘤细胞。 细胞系，AR 42 J，表现出正常产前的许多特性， 胰腺的rab蛋白的表达和分布 正常的分泌发生。发育中的腺体与 腺泡细胞瘤可能提供信息的潜在缺陷， 分泌物的特征，这种大鼠肿瘤的形态和几个 人类胰腺癌的类型。

The overall goals of our project are to determine the molecular basis of the biogenesis of regulated secretion in the developing pancreas. Our previous work has shown that 1 to 2 days prior to birth, acinar cells respond to secretagogue stimulation with elevations of intracellular second massagers levels but do not couple this event to exocytosis despite the observation that all of the organelles of the exocytic pathway are present. Regulated exocytosis in response to hormonal stimulation becomes functional approximately 24-48 hours after birth (secretogenesis). Our studies show that secretogenesis is correlated with movement of rab3D (a marker exclusively for zymogen secretogenesis is associated with a dramatic but transient appearance of rab4 (24-48 hour postnatally) in the apical cytoplasm of the cell where it colocalizes with the actin terminal web and not with membranes of the secretory or endocytic pathway. We postulate that the transient expression of rab4 is related to the maturation of an actin "clamp" that may be a terminal event the cascade of events leading to the maturation of regulated exocytosis. We intend to pursue this system further in order to determine the factors responsible for secretogenesis. Specific aims are (1) to characterize the physiological significance of rab3 and rab4 during secretogenesis with regard to state of phosphorylation, interaction with regulatory proteins (e.g., rab GDI and proteins that may be involved in actin binding), and to evaluate function in cell line, AR42J whose regulated secretory pathway can be hormonally induced and in which specific mRNAs for rab proteins are eliminated with anti-sense nucleotides; (2) to examine the expression of other small GTP-binding proteins and members of the SNARE family that may be developmentally regulated during secretogenesis; (3) to study secretogenesis in organ culture under defined conditions in order to determine the effect of candidate hormones on maturation of regulated secretion; and (4) to examine an acinar cell tumor and a derived inducible cell line, AR42J, that exhibits many of the properties of normal prenatal pancreas for expression and distribution of rab proteins involved in normal secretogenesis. Comparison between the developing gland and the acinar cell tumor may provide information on the potential defects in secretion that characterize the morphology of this rat tumor and several types of human pancreatic cancer.